Recent expansion of pharmacotherapy of inflammatory bowel diseases (IBD) reflects an increasing understanding of the mechanisms involved in its pathogenesis. Individual variation in response to drugs is a major problem in clinical practice and is associated with various host factors, including sex, age, diet, alcohol consumption, smoking habits and genetic background. The study of the genetic determinants influencing interindividual differences in drug responses is known as pharmacogenetics. A common disease as IBD may be caused by different groups of genes in different people, showing smaller genetic variation than IBD patients globally considered. The classification of individuals based on sets of susceptibility alleles will make treatment more predictable and effective. Pharmacogenetics in IBD is developing in two main directions. One involves the identification and design of novel drug targets by exploiting current knowledge of the structure and function of IBD susceptibility genes. Another thrust of IBD pharmacogenetic research is directed at understanding how genetic variation determines the response to and the side effects of existing therapeutic agents. Pharmacogenetics holds the promise that drugs might one day be adapted to each persons own genetic background and therefore be more efficacious and safe. Therapies of future should put emphasis on the epidemiological, molecular and genetic basis of disease with the application to clinical practice, underscoring the final goal of personalized medicine. In this review, we focused on the basis of pharmacogenetics, on the recent advances of the field in the main therapies involved in IBD (Azathioprine / 6-Mercaptopurine, 5-Aminosalicylates, Glucocorticoids, Methotrexate, Infliximab) and speculate on the future of pharmacogenetics.